1. package Scrollables is 
  2.  
  3.     pragma Preelaborate; 
  4.  
  5.     -- An interface for scrollable widgets. A widget implementing this interface 
  6.     -- declares that its viewport can be scrolled if it does not display the 
  7.     -- widget's entire content region. 
  8.     type Scrollable is limited interface; 
  9.     type A_Scrollable is access all Scrollable'Class; 
  10.  
  11.     -- Returns the widget's increment for scrolling in the X direction. 
  12.     function Get_Scroll_Inc_X( this : access Scrollable ) return Integer is abstract; 
  13.  
  14.     -- Returns the widget's increment for scrollign in the Y direction. 
  15.     function Get_Scroll_Inc_Y( this : access Scrollable ) return Integer is abstract; 
  16.  
  17. end Scrollables;